This invention relates to an improvement in methods and equipment to install columns of granular material in soil formations containing substantial quantities of water or other fluids to expedite the dissipation of water or fluid pressures induced by applied loads and stresses in order to expedite soil settlement and to render soil more stable and improve its capacity to safely support construction.
More particularly, this invention relates to an improvement in available methods and equipment to permit the installation of sand drains with diameters as small as 2" or less, heretofore considered uneconomic, in order to compete with small band shaped "wick drains" which are effectively replacing the use of sand drains.